Applied Mechanics and Materials Vols. 477-478

Abstract: This study systematically investigated how helium and oxygen (He/O₂) atmospheric pressure plasma jet (APPJ) treatment influences the size adhesion strength (SAS) to the cotton yarn. Results show that the SAS increases with the treatment time from 0 to 18 s then decreases until 24s. The SAS has a decreasing trend when the jet to sample distance (JTSD) goes up from 1.5 to 6.0 mm and it increases with the rising of O₂ flux from 0.1 to 0.3 L/min then decreases until 0.45 L/min. For samples with different moisture regains (MRs) of 0.5%, 9.3% and 26.3%, the SAS decreases as the MR rises up. SEM and XPS analyses show that APPJ treated samples have roughened surfaces and are introduced polar bonds such as COH, C=O and OC=O. Cotton fibers with lower MRs are more efficiently etched and more polar bonds are imparted by the APPJ treatment.

Abstract: The short life due to heavy wear is a bottleneck that limits the usage of mechanical excavators for hard rock cutting. Thermally stable diamond composite (TSDC) tipped cutting tools have the main advantages of good thermal stability, high wear resistance and ability to mine harder deposit compared to the conventional tungsten carbide (WC) tipped cutting tools. Super Material Abrasive Resistant Tool (SMART*CUT) based on TSDC tip has been developed by CSIRO to improve the effectiveness of cutting tools when dealing with hard deposit in mining and civil industries. In this study, the effects of attack angle and depth of cut on the cutting performance of SMART*CUT picks in different cutting orientations were investigated. A tri-axial dynamometer and a data acquisition system were used to measure the cutter forces. Normal force, cutting force and resultant angle were correlated with depth of cut and attack angle. Cutting performances were compared in different cutting orientations. The results would be beneficial to the selection of mechanical excavator motor and the optimization of cutting drum design to some extent.

Abstract: The paper takes the SRV friction and wear tester, conducts the research on the abrasive ability of the three tribomate pairs (ceramic piston ring and P-B, Cu-Cr-Ni-Mo and bainite cylinder bores) under the condition that there lies a certain amount of quartz sand in the lubricant and find that the more hardness of cylinder bores, the more capability of resisting abrasion. The capability of resisting abrasion of ceramic piston ring/bainite cylinder bores is the best in three tribomate pairs.

Abstract: The effect of processing parameters on the welding deformation of 304 stainless steel plates with different thickness were studied by using the pulsed Nd: YAG laser welding progress. Single factor experiment was used in this study. The results show that, in a certain range of parameters, the vertical deformation increases with the increment of the welding current, and decreases at the beginning and then increases with increment of the pulse duration and pulse frequency. However the increment rate of welding deformation decreases while the current value goes up. The welding deformation trends of the 304 stainless steels with different thickness stay the same in a certain range of processing parameters in terms of data collected from the experiment.

Abstract: Using laser cladding method, the coating of Fe-Mn-Si shape memory materials (SMM) was prepared on the surface of AISI 304 stainless steel. The microstructure and microhardness of SMM laser cladding coating were measured by using a metallographic microscope and a scanning electron microscope, respectively. The phase composition was determined by X-ray diffraction. The wear resistance was evaluated on a high speed reciprocating friction tester. The results show that microhardness of the SMM coating is about Hv263, higher than that of the substrate (Hv225); the SMM coating is composed of ε-martensite and γ-austenite phases; the average friction coefficient of the substrate and SMM coating is about 0.85 and 0.71; the SMM laser cladding coating is of excellent wear resistance validated by friction coefficient, worn-out appearance and wear loss.

Abstract: To improve the mechanical properties of the physical vapor deposition (PVD) coatings deposited on fine-blanking tools and increase the tool life, TiN and TiAlN coatings were deposited on the powder metallurgy high speed steel S790 substrates by Multi-arc ion plating, and then annealed at the temperature of 500°C for one hour in vacuum enviroment. The phase variation, residual stress, morphology, surface microhardness and adhesion strength of coatings were respectively analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers hardness tester and automatic scratch tester. The preferred orientations in the coatings are not changed after annealing, indicating no disparities in the crystal structure of the coatings. The residual stress of coatings released a little after annealing, however the adhesion strength between the coatings and substrates increased obviously, which indicated that the properties of the TiN and TiAlN coatings deposited on S790 steel were improved.

Abstract: Removed at authors request

Abstract: Laser quenching is an important heat treatment process which is used in many industries. It is necessary to ascertain the laser processing parameters before the process is performed. Therefore, a numerical simulation of the temperature field is a good way. This paper reports a numerical model for the temperature rise in the quenched zone of a cylindrical circumferential surface under laser spiral scanning quenching. In this method, the analytical solution is utilized of transient temperature field due to a moving point heat source. This model considers the effect of the adjacent quenched path on the base temperature of quenching performance and assumes a laser beam of a uniform intensity. The surface temperature field was computed based on the method. The analyses also indicate that the temperature at the later cycles area is much higher than that of the first cycles heated area. The practical value of this model will be a help for ascertaining the process parameters of laser spiral scanning quenching on cylindrical circumferential surface for an even temperature distribution.

Abstract: In this paper, copper was recovered from copper smelting slag by oxidation-ammonia leaching under normal pressure. Ammonia persulfate was employed as oxidizing agent and ammonia as complexing. The results showed that the optimal parameters were as following: the mass ratio of liquid and solid was 4:1, the temperature was 35°C, the leaching time was 180 minutes, the amount of (NH₄)₂S₂O₈ was 0.4 times of the slag sample, the ammonia concentration was 11mol/L. Under the optimal conditions, recovery of copper was 81.7%.

Abstract: Research on material properties under extreme conditions plays a great role in material science and high energy physics. Condensed liner accelerated by powerful pulse facilities has been used to compress the target liner. The motion of liner implosion driven by a pulse of current of several microseconds rise time and 70~90 MA has been numerically studied in this paper. Liners state and velocities are discussed. Results of 2D magnetohydrodynamics liner implosion computations are presented in order to study the development of interface instability.